Issuu on Google+

This article appeared in a journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier’s archiving and manuscript policies are encouraged to visit: http://www.elsevier.com/copyright


Author's personal copy

Indian Journal of Dentistry 2012 OctobereDecember Volume 3, Number 4; pp. 213e221

Review Article

Development in techniques for gingival depigmentation e An update Santhosh Kumara,*, G. Subraya Bhatb, K. Mahalinga Bhatc

ABSTRACT Dental esthetic needs of patients are increasing with a greater demand on pleasing look. This demand gets fulfilled not only by having healthy set of dentition but also esthetically improved gingival component. Gingival melanin pigmentation is one of the factors which determine the smile of an individual. Based on the available literature gingival melanin pigmentation can vary depending on whether it is physiological or pathological. Its esthetic importance depends on the skin complexion of the patient and is one of the most important factors for determining the treatment for gingival melanin pigmentation. It is necessary to select an appropriate technique for treating unaesthetic gingival melanin pigmentation of patients and the treatment should cause minimal discomfort and should be effective for a longer period of time. Treatment of gingival melanin pigmentation can be done using scalpel, chemical agents, abrasion, grafts, electro surgery, cryosurgery or lasers. Recent reports on treatment of gingival melanin pigmentation using cryosurgery and lasers show results in terms of ease of use, acceptance and patient comfort to be far superior to other techniques. This literature review is done to classify and explore the recent treatments and future procedures available for depigmentation. Keywords: Gingiva, Melanin, Pigmentation, Physiologic, Pathologic, Cryosurgery, Electro surgery, Lasers

INTRODUCTION Melanin is non-hemoglobin derived brown pigment, most common of the endogenous pigments. It is a derivative of tyrosine and is synthesized in the Melanocytes. The Melanocytes are embryologically derived from neural crest ectoderm. In the human fetus it enters the epidermis and presumably the oral epithelium from the eleventh week onwards.1 Once in the epithelium these cells constitute a self-producing population normally situated within the basal layer of the fully developed human epidermis, although they have been observed supra basally in human oral epithelium.2 Melanin is a powerful cation chelator and may act as a free radical sink.3 It is used commercially as a component of photoprotective creams, although mainly for its free radical scavenging rather than its light absorption properties. The pigment is also a potential target for anti-melanoma therapy.4

Gingival melanin pigmentation does not usually present as a medical problem, but patients may complain that their black gums are unaesthetic. This problem aggravates in patients with a “gummy smile” or excessive gingival display while smiling or talking.5e7 Cryosurgery and lasers being the newer and recent applications, these are considered to be more acceptable not only by the clinicians but also by the patients than other traditional methods.

CHARACTERISTICS OF MELANIN PIGMENT Examination of human Melanocytes with the electron microscope has shown these cells to be similar in epidermis and oral epithelium. The cells differ from adjacent epithelial cells in being dendritic, lacking desmosomes and tonofibrils and in having a well-developed Golgi region and large

a Assistant Professor, bProfessor and Head, cProfessor, Department of Periodontics, MCODS, Manipal 576104, Manipal University, Udupi District, Karnataka, India. * Corresponding author. Tel.: þ91 9741968550; fax: þ91 8202571966, email: drsanthoshkumar@gmail.com Received: 26.1.2012; Accepted: 21.5.2012 Ó 2012 Indian Journal of Dentistry. All rights reserved.

http://dx.doi.org/10.1016/j.ijd.2012.05.007


Author's personal copy

214

Indian Journal of Dentistry 2012 OctobereDecember; Vol. 3, No. 4

areas of rough endoplasmic reticulum. These latter features are consistent with the secretory role of the cell in the production of melanin. (Fig. 1) The result of the oxidation of tyrosine via number of intermediate components, including di-hydroxy phenyl alanine (DOPA) is the formation of the dense pigment melanin, which obscures the striations seen on the premelanosome to form the homogeneous, opaque melanosomes. Initially it was assumed that melanoid was a degradation product of melanin, but more recently it has been shown that such a relationship is highly improbable. Melanoid imparts a clear yellow shade to the skin.8 Approximately the number of Melanocytes seen in any given region of the skin is same. Thus the ratio of Melanocytes to basal epidermal cells in caucasoid and blacks varies from approximately 1:4 on the cheek to 1:11 over the thighs

Kumar et al.

and arms. Little data are available for the oral mucosa although Fitzpatrick & Szabo quote an overall figure of 1:7 and a ratio of 1:15 have been found in human gingival epithelium.1 Differences in pigmentation of a given region are thus a function of the activity, rather than the number of Melanocytes and even in conditions of hypopigmentation such as albinism where ‘amelanotic’ Melanocytes are still present. The differences in amount and distribution of these pigments account for the variation in skin color between the sexes and between different parts of the body. In examination of persons of various races,9 it has been found that color difference between races are based only on the production of various amounts of primary ectodermal melanin and melanoid, the amount of all other pigments being the same in all races.

CLASSIFICATION Dummett and Barrens (1971) in their review divided oromucosal pigmentation in following categories. (1) Local and ethnic pigmentations (2) Oral pigmentary manifestations of systemic diseases10 (3) Pigmentary disturbances associated with pharmaceutical and other chemicals (4) Benign and malignant neoplasms of pigmentary origin. Bradley Grace et al (2004)11 Classification based on the distribution of the pigmentation.

Diffuse and bilateral Early onset: Physiological pigmentation, Peutz jegher’s syndrome. Predominantly adult onset With systemic signs and symptoms Addison’s disease,12 Heavy metal pigmentation, Kaposis sarcoma, No systemic signs and symptoms Drug induced pigmentation, Post inflammatory, Smokers Melanosis.13

Focal Fig. 1 The basal layer of the gingiva contains Melanocytespigment containing cells which give a brownish hue to portions of the gingiva. There are also a few cells in the connective tissue which have taken up melanin granules e melanophores.

Red e blue e purple Blanching: Hemangioma, varix Non blanching: Thrombosis, Hematoma Blue gray: Amalgam tattoo, Other foreign body tattoo, Blue nevus


Author's personal copy

Development in techniques for gingival depigmentation

Brown: Melanotic macule, Pigmented nevus, Melano acanthoma, Melanoma Gingival melanin pigmentation is measured using the following index. Gingival pigmentation index:

Review Article

215

Ascorbic acid Ascorbic acid (AS-G gel) was used by Yashuko shamida et al15 for depigmentation and found that it significantly inhibited tyrosinase activity and melanin formation in B16 mouse melanoma cells. The inhibitory effects of ascorbic acid on melanin formation were also significant in threedimensional human skin models. They concluded that ASG has potential for the treatment of gingival melanin pigmentation.

Surgical methods of depigmentation

MANAGEMENT OF GINGIVAL MELANIN PIGMENTATION Different techniques employed for gingival depigmentation.

Chemical methods of depigmentation using caustic chemicals Most commonly used are phenols and alcohol. The treatment was not acceptable to the clinicians or the patients. In 1951 Hirschfield and Hirschfield14 used a mixture of phenol (90%) and alcohol (95%) to burn out the pigmented gingiva by destroying tissue down to and slightly below the basal layer of the mucous membranes.

Several surgical methods of depigmentation available which can be performed under local anesthesia: B

Gingival-abrasion technique Split thickness epithelial excision B Combination technique (gingival abrasion and split thickness epithelial excision) B Free gingival grafting (Fig. 2) B

Gingival abrasion technique In this technique a medium grit football shaped diamond bur is used at high speeds to denude the epithelium. The procedure requires 45 min to 1 h for completion. Healing by reepithelialisation occurs within 7e10 days.15 It is relatively non invasive, a cost effective technique and it doesn’t require specific

Fig. 2 (A) Cryosurgical, (B) gingival abrasion, (C) laser and (D) radiosurgery16 techniques for gingival depigmentation.


Author's personal copy

216

Indian Journal of Dentistry 2012 OctobereDecember; Vol. 3, No. 4

instrument. Procedural discomfort, placement of periodontal pack, duration of procedure, recurrence of pigmentation and technique sensitivity are few of the drawbacks of this procedure.

Scalpel surgical technique or split thickness epithelial excision technique This procedure essentially involves surgical removal17 of gingival epithelium along with a layer of the underlying connective tissue and allowing the denuded connective tissue to heal by secondary intention. Dummett and Bolden (1963)18 reported in a study that Scalpel surgery can cause unpleasant bleeding during and after the procedure. It is essential to cover the exposed lamina propria with a periodontal pack for 7e10 days. Delicate scarring, exposure of the alveolar bone at areas where the gingiva is thin and repigmentation can be few of the disadvantages of the procedure.19 Free gingival grafting Described by Tamizi, Taheri (1996)20 for treating severe physiologic melanin pigmentation requires replacement with an unpigmented free gingival autograft. The result of this procedure showed no evidence of repigmentation even after 4.5 years. Of the 10 treated patients only 1 patient showed repigmentation after 1 year. But the disadvantage of this procedure included two surgical sites, ghost like appearance of the treated site due to hypopigmentation and technique sensitivity. Acellular dermal matrix allograft Acellular dermal matrix with partial thickness flap has been used in the elimination of gingival melanin pigmentation. It can be a substitute for gingival autograft.21

RECENT METHODOLOGIES IN GINGIVAL DEPIGMENTATION

Kumar et al.

chromium-doped: yttrium, scandium, gallium, garnet (Er,Cr: YSGG) (2780 nm) lasers. In the case of laser depigmentation, the ability of melanin-containing Melanocytes to absorb the laser light is dependent on the wavelength of the laser and its ability to penetrate tissue. Melanin has an absorption spectrum range between 351 and 1064 nm. The diode lasers used in dentistry have wavelength spectrum ranging from 800 to 980 nm, which allows high levels to be absorbed by soft tissue, water, and chromophores, such as melanin and oxyhemoglobin and considered ideal for depigmentation procedure. In contrast, Er: YAG lasers produce invisible infrared light at a wavelength of 2940 nm, which is ideal for absorption by hydroxyapatite and water, but which does not coincide with the absorption spectrum of melanin.22 Therefore, in cases of gingival hyperpigmentation, Er: YAG lasers are advantageous in limiting thermal damage but at a disadvantage regarding depigmentation. Because the Er: YAG wavelength corresponds to the absorption coefficient of water, laser irradiation transforms water within tissue into steam, producing thermomechanical “microexplosions”. The Er: YAG laser is able to remove excessive melanin by ablating tissue in the suprabasal and basal layers of the epithelium. (Table 1)

Carbon dioxide laser Carbon dioxide laser is one of the most practically used lasers. With the CO2 laser, the rapid rise in intracellular temperature and pressure leads to cellular rupture, as well as release of vapor and cellular debris, termed the laser plume. Char formation occurs more rapidly during the continuous wave mode than with pulsed or gated modes. Removal of gingival melanin pigmentation should be performed cautiously and the adjacent teeth should be protected, since inappropriate application may cause gingival recession, damage to underlying periosteum and bone, delayed wound healing and loss of enamel. The histological

Lasers

Table 1 Properties depigmentation.22,23

Lasers have become widely used in medicine and surgery since the development of the Ruby laser by Maiman in 1960. Laser ablation for gingival depigmentation has been recognized as one of the most effective, pleasant, and reliable techniques. Different lasers have been used for gingival depigmentation, including Carbon dioxide (CO2) (10,600 nm), Diode (820 nm), Neodymium-doped: Yttrium, Aluminum, and Garnet (Nd:YAG) (1064 nm), Erbium (Er)-doped:YAG (2940 nm) and Erbium- and

Lasers Argon KTP Diode Nd: YAG Ho:YAG Erbium Co2

of

different

lasers

used

for

Medium

Wavelength

Absorbed by

Gas Solid Solid Solid Solid Solid Gas

488e514 nm 532 nm 810e980 nm 1064 nm 2120 nm 2790e2940 nm 9600e10,600 nm

Hgb, melanin, resins Hgb, melanin Melanin, Hgb Melanin, Hgb Water, dentin Water, hydroxyapatite Hydroxyapatite, water


Author's personal copy

Development in techniques for gingival depigmentation

sections showed that the CO2 beam removed the epithelium in layers in a scalloping mode accurately following the wavy surface until it reached the basement membrane, without touching the connective tissue.24

Nd: YAG The 1064 nm Nd: YAG laser will penetrate water to a depth of 60 mm before it is attenuated to 10% of its original strength. The Nd: YAG laser is set at 6 W, 60 mJ per pulse, and 100 pulses per second. The procedure is performed with contact mode in all pigmented areas by using a handpiece with a 320 micron diameter fiber optic. Ablation of the gingival hyperpigmented areas were accomplished without any bleeding, complications or significant post operative pain. Astawasuvan (2000)25 did a study to depigment using q-switched Nd: YAG laser. Following 3e4 weeks after the procedures, the hyperpigmented gingiva appeared healthy, pink, and firm. No recurrence of hyperpigmentation had been found in 11e13 months of follow-up. Diode laser It has also been introduced over the past few years for dental use, obtaining FDA safety clearance. It also can be delivered through a flexible quartz fiber optic handpiece and has a wavelength of 819 nm. This energy level is absorbed by pigmentation in the soft tissues and makes the diode laser an excellent hemostatic agent. The amount of power to be applied was determined based on the clinical experience of the operators and the manufacturer’s recommendations. The procedure was performed with the handpiece at a distance of 5 mm from the gingiva and using a diffused beam in a contact mode and from a cervical-apical direction in all pigmented areas. The operative site was cooled using high vaccum or cooling pumps instead of water. Diode and Er: Yag lasers administered at 1 W both results in satisfactory depigmentation of gingival melanin pigmentation.26 Laser patterned microcoagulation The laser microcoagulation treatment is a quasi-periodic pattern of columns covering a pigmented spot, in which each column is created by application of a single laser pulse from a diode laser system. A diode laser operating at 980 nm wavelength and generating up to 20 W of power was used. The delivery system had replaceable tips with 0.6 mm diameter. In this case, each column was created by an 80 ms pulse. No anesthesia was used.27 Repigmentation following laser can be due to spontaneous phenomenon and may result because of migration of Melanocytes from

Review Article

217

the surrounding tissues. Hence it is necessary to adequately de-epithelialize for treatment of melanin pigmentation.

Cryosurgery or cryotherapy Cryosurgery is that branch of therapeutics which makes use of local freezing for the controlled destruction or removal of living tissues.

Cryosurgery The effect of low temperature on living tissues have been the subject of fascinating studies since Robert Boyle reported almost 300 years ago that cells were killed by freezing. The biologic effect of physical factors such as cold behaves like ionizing radiation and the maximum lethal effect is obtained when they are applied to cells undergoing mitosis. Most vital tissues freeze at approximately 2  C, Ultra low temperature (below 20  C) results in total cell death.28

The cryogens Cryogen is a substance used for cryosurgery. Over the years, several cryogens have been used. They include the following. Cryogen effective temperature: Salt ice 20  C, CO2 slush 20  C, Fluorocarbons (Freons) e 30  C, Nitrous oxide 75  C, CO2 snow 79  C, Liquid nitrogen 20  C (swab) 196  C (spray), Tetrafluoroethane 20  C to 40  C.29 A colorless, nonchlorofluorocarbon, nonflammable gas, 1,1,1,2 tetrafluoroethane (TFE) is usually used as coolant or refrigerating systems and electronic circuits. There are human and animal toxicology studies evaluating the safety of TFE.30,31 Cryosurgical procedure The dose of cryogen and the choice of delivery method depend on the size, tissue type, and depth of the lesion. The area of the body on which the lesion is located and the required depth of freeze also should be considered. Additional patient factors to consider includes the thickness of the epidermis and underlying structures, the water content of the skin, and local blood flow.32 1) Dipstick method 2) Spray technique 3) Cryoprobe technique


Author's personal copy

218

Indian Journal of Dentistry 2012 OctobereDecember; Vol. 3, No. 4

Spray technique using spray tip This is also known as Open-spray technique. The hand held or table top cryosurgical unit filled with liquid nitrogen is used, Select a spray tip that sprays within the border of the lesion. For single short freeze, no local anesthesia is required. But if the lesion is large and requires more freeze time, then 1% lignocaine is given. The spray tip is held 1 cm away from the lesion and a steady spray of liquid nitrogen is directed at the centre of the lesion. Freeze time commences once the solid ice has formed over the entire area. The lesion is allowed to thaw slowly i.e. come back to room temperature. Thaw time is usually double of freeze time. Cryoprobe technique In this technique, liquid nitrogen is circulated so as to cool the tip of the cryoprobe, which is to be applied to the lesion. Hence, freezing occurs by conduction. This technique is slower than spray technique. The depth of penetration of the ice ball is difficult to estimate and prolonged freezing could cause excessive tissue destruction.33 The shelf life of liquid nitrogen is not adequate for storage for long periods due to its faster rate of evaporation even in closed container. Discomfort like stinging, burning sensation or pain (on prolonged freezing) is experienced during the procedure.

Clinical changes following cryosurgery The tissue freezes solid taking on the appearance of a ball of ice. Thawing occurred in 15e20 s with progression from the periphery to the center of the ice ball. At 12 h an elevated white fluid filled blister appeared which increased in size slightly up to 24 h. The roof of the blister area consisted of a white membrane, outlined by an indistinct red halo. At 48 h the blister ruptured, exposing a smooth underlying surface. At the periphery, the ragged blister membrane still remains discernible. Repair and reepithelization takes place deep to the slough, which separates off after leaving a clean surface.34

Kumar et al.

In 1970 Mayer P.D et al28 conducted a clinical study to evaluate the histological reaction of clinically normal gingiva to freezing. They observed unusual multinucleated giant cells in epithelium near the periphery of the frozen area after 12 h. They also found that surface repair was completed between 24 and 48 h of injury. Tal et al33 selectively treated epithelium on gingival flap surface by ultra low temperature for 5 s using a gas expansion cryoprobe cooled to 81  C. The authors concluded that low cryodose can effectively destroy oral gingival epithelium without causing significant morphologic damage to the underlying lamina propria. In a 2e5 year clinical observation by Haim Tal32 after superficial cryosurgical treatment of moderate to heavy pigmented gingiva in seven nonsmoking patients, the sites were exposed to a gas expansion cryoprobe cooled to 81  C for 10 s. Patients did not report side effects, nor did they require additional treatment during the 5year period after surgery. In a simple and effective cryosurgical technique to eliminate the pigmentation Chin-Jyh Yeh16 in subjects of abnormal deposition of melanin in gingiva in twenty patients with dark gingiva were treated by direct application of liquid nitrogen with a cotton swab for 20e30 s. The treated gingiva appeared normal within 1e2 weeks after 1 or 2 cryosurgical treatments, the acceptance of the treatment was excellent. This was a simple, bloodless cryosurgery for the depigmentation of gingiva, requiring no local anesthesia or sophisticated equipment. Fatih Arikan7 used Tetrafluoroethane (TFE) cooled cotton swab application in the cryosurgical depigmentation of gingiva. He concluded that TFE may be used as an offlabel product with minor complications in melanin depigmentation of gingiva. Shaeesta K. A34 performed gingival cryosurgery in segments in the maxillary anteriors, each segment measuring w5  w5 mm was exposed to a gas expansion cryoprobe using nitrous oxide, and the cryoprobe was cooled to 70  C to 90  C for 30 s. Immediately after

Fig. 3 (A) Pre-operative, (B) Post-operative pictures following gingival depigmentation.


Author's personal copy

Development in techniques for gingival depigmentation

Review Article

219

Table 2 Requirements and acceptability of various techniques. Gingival abrasion Local anesthesia Technique Ease of performing Discomfort/ pain Periodontal dressing Healing Final appearance Repigmentation

Cost

Cost effective

Split thickness excision technique

Free gingival graft

Lasers

Cryosurgery

Required

Required

Required

Not required

Not usually

Non invasive Technique sensitive

Invasive Technique sensitive

Invasive Technique sensitive

Non invasive Technique sensitive

Non invasive Relatively easy

Minimal

Minimal

Mild to moderate

No discomfort

Pricking pain

Necessary

Necessary

Necessary

Not necessary

Not necessary

1e2 weeks Papillary gingiva shows pigmentation Seen (9 months)

1e2 weeks Complete

2e3 weeks Ghost like appearance (Hypopigmented areas) Not seen

Within a week Complete depigmentation Recurrence 1e3 months

Within a week Complete depigmentation Not seen

Cost effective

Expensive

Cost effective

Not seen (duration can vary from 33 to 120 days) Cost effective

Table 3 Advantages and major disadvantages of different techniques for depigmentation. Techniques Scalpel surgery Laser Cryosurgery

Radiofrequency

Liquid nitrogen Tetrafluoroethane

Advantages

Major disadvantage

Cost affordability Ease of access to interdental papilla Easy to perform Easier and takes less time

Bleeding Expensive Safety Sometimes needs more than one application/appointment Expensive

Ease of access to interdental papilla

removal of the cryogenic probe, the tissue was frozen solid, taking on the appearance of a ball of ice. Thawing occurred in 15e20 s with progression from the periphery to the center of the ice ball. Thirty minutes after freezing, the tissue area was indiscernible from adjacent gingiva. (Fig. 3)

Radiosurgery Radiosurgery uses a 4 MHz radio signal to produce a fine microsmooth incision with no overt lateral heat being sent to the surrounding tissues. A superficial effect is sufficient to remove pigmentations. Touching the pigmented areas lightly with the No. 135 ball shaped electrode or tapping the area with the No. 134 L-shaped electrode when the Ellman Surgitron or Radiolase II is operating will successfully treat a case with gingival melanin pigmentation. This method atleast required two sittings for completion within 2 weeks of treatment.35 (Tables 2 and 3)

CONCLUSION Based on the available literature gingival melanin pigmentation can vary depending on whether it is physiological or pathological, based on the location, color or it can be traumatic. The most important factor for determining the treatment for gingival melanin pigmentation is the type of pigmentation, patient acceptance of treatment procedure, its prevalence and its esthetic importance depending on the skin complexion of the patient. Treatment of the melanin pigmentation using older methods like gingival abrasion, scalpel depigmentation, free gingival graft were time consuming, painful, required placement of periodontal dressings, uneven treated areas and showed results for only a short period of time than cryosurgery or lasers which shows better results and faster outcome with minimal post operative complications. Future shows bright outcome for the selection criteria for depigmentation in terms of cryosurgery using TFE or diode laser. Both the procedure are better for depigmentation procedure


Author's personal copy

220

Indian Journal of Dentistry 2012 OctobereDecember; Vol. 3, No. 4

whilst cryosurgery being slightly better than modern lasers for depigmentation.

CONFLICT OF INTEREST All authors have none to declare.

REFERENCES 1. Fitzpatrick TB, Szabo G. The melanocytes: cytology and cytochemistry. J Invest Dermatol. 1959;32:197. 2. Cicek Y. The normal and pathological pigmentation of oral mucous membrane: a review. J Contemp Dent Pract. 2003 Aug;4(3):76e86. 3. Riley PA. Melanin. Int J Biochem Cell Biol. Nov 1997;29(Issue 11):1235e1239. 4. Trelles MA, Verkruyesse W, Segui JM, Udeata A. Treatment of melanotic spots in the gingiva by argon laser. J Oral Maxillofac Surg. 1993 July;51(7):759e761. 5. Roshna T, Nandakumar K. Anterior esthetic gingival depigmentation and crown lengthening: report of a case. J Contemp Dent Pract. 2005;15:139e147. 6. Azzeh Manal M. Treatment of gingival hyperpigmentation by erbium-doped:yttrium, aluminum, and garnet laser for esthetic purposes. J Periodontol. Jan 2007;78(1):177e184. 7. Arikan Fatih, Gurkan Ali. Cryosurgical treatment of gingival melanin pigmentation using tetrafluoroethane. Oral Surg Oral Med Oral Pathol. 2007 Apr;103(4):452e457. 8. Regezi, Scuibba. Text book of oral pathology e clinical e pathologic correlation. 5th ed.; 2008. 31e34. 9. Dummett CO. Physiologic pigmentation of the oral and cutaneous tissues in the negro. J Dent Res. 1946 Dec;25(6): 421e432. 10. Adour KK. Oral manifestations of systemic diseases. Med Clin North Am. 1966 Mar;50(2):361e369. 11. Grace Bradley, Blanas Nick, Pavone Marisa, Kauzman Adel. Pigmented lesions of the oral cavity: review, differential diagnosis and case presentations. J Can Dent Assoc. 2004;70(10): 682e683. 12. Choung Robert, Goldberg Morton H. Oral hyperpigmentation associated with Addison’s disease. J Oral Maxillofac Surg. 1983 Oct;41(10):680e682. 13. Hedin CA, Axell Tony. Oral melanin pigmentation in 467 Thai and Malaysian people with special emphasis on smoker’s melanosis. J Oral Pathol Med. 1991;20(1):8e12. 14. Hirschfeld I, Hirschfeld L. Oral pigmentation and a method of removing it. Oral Surg Oral Med Oral Pathol. 1951;4: 1012e1016.

Kumar et al.

15. Shimada Y, Tai H, Tanaka A, et al. Effects of ascorbic acid on gingival melanin pigmentation in vitro and in vivo. J Periodontol. 2009;80:317e323. 16. Yeh Chin-Jyh. Cryosurgical treatment of melanin-pigmented gingiva. Oral Surg Oral Med Oral Pathol. 1998;86(6): 660e663. 17. Ginwalla TM, Gomes BC, Verma BRR. Surgical removal of gingival pigmentation (a preliminary study). J Indian Dent Assoc. 1966;38:147. 18. Dummett CO, Bolden TE. Post surgical clinical repigmentation of the gingiva. Oral Surg Oral Med Oral Pathol. 1963;16:353e365. 19. Bergamaschi O, Kon S, Doine AI, Ruben MP. Melanin repigmentation after gingivectomy: a 5-year clinical and transmission electron microscopic study in humans. Int J Periodontics Restorative Dent. 1993;13(1):85e92. 20. Tamizi M, Taheri M. Treatment of severe physiologic gingival pigmentation with free gingival autograft. Quintessence Int. 1996;27(8):555e558. 21. Novaes AB Jr, Pontes CC, Souza SL, Grisi MF, Taba M Jr. The use of acellular dermal matrix allograft for the elimination of gingival melanin pigmentation: case presentation with 2 years of follow-up. Pract Proced Aesthet Dent. 2002 Oct;14(8):619e623. 22. Meserendio Leo J, Pick Robert M. Lasers in dentistry Chicago: quintessence, 1995. J Am Dent Assoc. 1995;126:1354e1356. 23. Moshonov J, Stabholz A, Leopold Y, Rosenberg I, Stabholz A. Lasers in dentistry. part Beinteraction with biological tissues and the effect on the soft tissues of the oral cavity, the hard tissues of the tooth and the dental pulp. Refuat Hapeh Vehashinayim. 2001 Oct;18(3e4):21e28. 107e8. 24. Wigdor HA, Walsh JT, Featherstone JDB, et al. Lasers in dentistry. Lasers Surg Med. 1995;16(2):103e133. 25. Atsawasuwan P, Greethong K, Nimmanon V. Treatment of gingival hyperpigmentation for esthetic purposes by Nd: YAl laser report of 4 cases. J Periodontol. 2000;71: 315e321. 26. Gupta GJ. Management of gingival hyperpigmentation by semiconductor diode laser. Cutan Aesthet Surg. 2011 Sep;4(3):208e210. 27. Allen, Gladkova, Fomina, et al. Successful gingival depigmentation with laser-patterned microcoagulation: a case report. Clin Adv Perio. 2011;1(3):210e214. 28. Meyers PD, Tussing Gerald, Wentz Frank M. The histological reaction of clinically normal gingiva to freezing. J Periodontol. 1971;42(6):346e352. 29. Bishop K. Treatment of unsightly oral pigmentation: a case report. Dent Update. 1994;21(6):236e237. 30. Ellis M, Gowans L, Green T, Tanner R. Metabolic fate and disposition of 1,1,1,2 tetrafluoroethane (HCF134a) in rat following a single exposure by inhalation. Xenobiotica. 1993;23(7):719e729.


Author's personal copy

Development in techniques for gingival depigmentation

31. Emmen HH, Hoogendijk EM, Klopping-ketelaars WA, Muijser H, Duistermaat E, Ravensberg JC. Human safety and pharmacokinetics of the CFC alternative propellants HCF 134a (1, 1, 1, 2 tetrafluoroethane) and HCF 227 (1, 1, 1, 2, 3, 3, 3 -hepatoflouropropane) following whole-body exposure. Regul Toxicol Pharmacol. 2000;32(1):22e35. 32. Tal Haim, Landsberg Jacob, Kozlovsky Avital. Cryosurgical depigmentation of the gingiva. A case report. J Clin Periodontol. 1987;14:614e617.

Review Article

221

33. Frazer J, Gill W. Observations on ultralow-frozen tissue. Br J Surg. 1967;54:770e776. 34. Sheetra KA, Joann PG, Prabhuji MLV, lazarus Flemingson. Cryosurgical treatment of gingival melanin pigmentation e a 30 month follow up case report. Clin Adv Perio. 2012;2(2):73e78. 35. Sherman JA, Gürkan A, Arikan F. Radiosurgery for gingival melanin depigmentation. Dent Today. 2009 Jan;28(1): 120e121.


Depigmentation